Solenoid with plunger



June 29, 1A948 H. sNYDE ,2,444,118

soLsnID wma rumena Filed )latch 27, 1946 52 /nVEn/"UF Fatenied `lune Q9, i948 rilialil SOLENOID WITH PLHJNGER Leland H. Snyder, hicago, im., assigner, by mesne assignments, to Quality Appliances, Ine., Chicago, lil., a corporation of Iliinois Application March 27, 1946, Serial No. 657,399

4 Claims.

This invention relates to improvements in elec- -tric solenoids.

'I'his application constitutes a continuation-inpart of my copending application Serial No. 619,353, led September 29, 1945, now U. S. Patent No. 2,427,630, and provides a solenoid construc- 'tion similar to that disclosed in my copending a solenoid which may be readily adjusted to vari1 the stroke and intensity of the magnetic pull thereof.

A particular object of this invention is to provide an improved solenoid construction requiring a minimum number of parts and susceptible Vto large quantity, low cost production methods for their manufacture.

The speciilc nature of the invention as well as other objects and advantages thereof will become apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of preferred example only, illustrates one specific embodiment of the invention.

On the drawing:

Figure 1 is a top elevational view of a solenoid construction embodying this invention.

Figure 2 is a side elevational view of the solenoid of Figure l.

Figure 3 is an enlarged scale vertical sectional view of the solenoid of Figure 1 taken along the plane III-III thereof.

As shown on the drawing:

A solenoid construction embodying this invention is indicated on the drawing generally by the numeral I and essentially comprises an annular core member 2, a winding 4, a casing 6, a cover 8, a plunger l0, and an adjustable core piece I2.

. The annular core member 2 is formed from magnetic material and denes an axial, cylindrical core opening I4. On each end of the core member 2, integral, radially projecting anges i6 are provided, and in the space between such ilanges I6, the coils of the winding 4 are mounted on the exterior of the core member 2 in circumferential relationship to the axis thereof.

The casing 6 is also formed from magnetic material and comprises a hollow cylindrical member dening a cylindrical chamber I8 and having one integral end wall 28 thereof shaped in re-entrant fashion to dene a small end opening 22 coaxially aligned with the chamber I8. Suitable interior threads are provided in end opening 22.

The other end opening 24 to chamber I8 is suiiiciently largeto permit the insertion of the annular core 2 and its associated winding 4 into the chamber I8 of casing 6. To close the large end opening 24 of casing 6, and further, to retain the core 2 snugly within the casing 6, a cover plate 8 is provided which is secured across the large end opening 24 of casing 6. Preferably cover plate 8 is secured to casing 6 through the cooperation of a plurality of peripherally spaced, integral tabs 26, which are provided on the casing 6 around the large end opening 24, with correspondingly located slots 28 provided in a peripheral portion 30 of cover plate 8 which extends beyond the periphery of casing 6. After insertion of tabs 26 through slots 28, the tabs 26 are bent over and thus firmly secure the cover plate 8 to casing 6.

The cover plate 8 is also formed from magnetic material and preferably has a portion of its inner surface, such as the integrally formed, central raised portion 32 disposed in metallic engagement with the adjacent end face of annular core member 2 and proportioned so as to urge the core member 2 tightly into engagement with the inner face of the opposite end wall 20 of casing 6 when cover plate 8 is assembled to the casing 6. With this construction, it will be apparent that a completely closed magnetic circuit is thus provided surrounding the coils or winding 4, formed by the core member 2, the casing 6, and the cover plate 8. It is thus assured that the winding d will produce a substantial amount of magnetic flux in the aforedescribed magnetic circuit and hence a powerful action can be obtained from the solenoid by a moderate voltage applied thereto.

The actuating plunger I0 of the solenoid construction comprises a bolt-like member having a cylindrical head portion 34 and a smaller diameter shank portion 36 secured thereto which projects out of casing 6 through a central hole 38 provided in cover plate 8. To prevent the passage of dust or other deleterious material into the interior of casing 6, a. seal 48 of rlber or rubber-like material is provided between the central opening 38 of cover plate 8 and the shank portion 36 of actuating plunger I8. Likewise, the leads 42 by which voltage is applied to the solenoid winding 4 from a suitable power source (not shown) are brought 3 through cover plate 8 through a fiber grommet 44 disposed in a suitable hole.

The head portion 34 of actuating plunger I0 is freely slidable within the central core opening i4 of the annular core 2. 'I'he actuating plunger I is biased in an axial direction tending to remove head portion 34 from central core opening I4 by a spring 46 disposed onv the shank portion 36 of plunger In exteriorly of casing 6 and which operates between the seal 40 and a suitable nut 48 which is threadably secured on the end of shank portion 36. The shoulder 50 formed by the juncture of shank portion 36 with head portion 34 of the actuating plunger eifectively limits the outward movement of the plunger under the bias of spring 46 by engagement with the inner face of the seal 40. If desired, the end of shank portion 36 may be provided with a reduced diameter threaded portion 52 by which the mechanical connection of the solenoid plunger to any desired device to be operated may be accomplished.

' It should be further noted that, if desired, a

flexible, resilient sealing member (not shown) may be mounted between the end of actuating plunger I0 and the projecting flange portion 36 of cover plate 8 in a manner similar to the mounting of the seal member described in my copending application.

An adjustable core piece i2 is provided comprising a threaded stud which is threadably engagedin the small opening 22 provided in end wall 20 of casing 6 and projects into the central core opening I4 an adjustable distance, depending upon how far it is screwed into the threads of opening 22. A suitable tool-engaging slot 54 may be provided in the exterior face of adjustable core member l2 to permit the convenient rotational adjustment thereof and a lock nut 56 may be provided to lock the core member I2 in any desired adjusted position.

The interior end of core piece l2 thus provides an adjustable air gap 58 between itself and the adjacent end face of the head portion 34 oi.' the actuating plunger I0. As is apparent on the drawings, the core 2 is of relatively thin walled construction, and may be conveniently formed `by stamping. Hence the core 2 has appreciable magnetic reluctance and saturates rupon the application of a relatively small magnetizing force by current flow through the winding 4. The reluctance'of the core 2 is therefore greatly reduced by the insertion of the actuating plunger I il within the core 2, particularly when the plunger Ill is moved into abutment with core piece i2 to close air-gap 58. Since every magnetic circuit exerts a force on the elements thereof to move such to a minimum reluctance position it is obvious that upon energization of the winding 4, a magentic force will be exerted upon the actuating plunger |0 in a direction to close the air gap 58. Upon the cessation of such energization, however, the spring 46 immediately returnsthe actuating plunger l0 to the position shown in Figure 3 of the drawing and thus reestablishes the air gap 56. The spring 46 is sulciently strong that when alternating current of commercially available frequency is applied to the winding 4, the spring will return the actuating plunger I6 to its deenergized position each time that the alternating current passes through its zero value. Accordingly, the actuating plunger i0 will be reciprocated rapidly at a frequency dependent upon the frequency of the applied voltage.

To further guide the reciprocating movement K of plunger I 6, and to eliminate the necessity of metallic engagement between the exterior surface of the head portion 34 of the plunger and the in'- terior surface of core opening I4, a pin 60 of suitable non-magnetic, metallic material may be secured into the end face of the head portion 34 of plunger In and cooperates in bearing relationship with an aligned hole 62 provided in the core piece i 2.

From the construction described, it will be apparent that this invention provides an improved solenoid having a minimum number of component parts and characterized by the simplicity of such component parts and their adaptability to manufacture by large quantity production processes. The assembled solenoid is of rugged construction, substantially dust-proof, and the stroke of the actuating plunger may be conveniently adjusted without requiring the disassembly of the solenoid.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In a solenoid construction having an annular magnetic core defining a central opening therethrough and a circumferentially disposed windingl on said core, the improvements of a hollow cylindrical magnetic casing having one integrally formed end wall, said casing being yconstructed and arranged to surround said core and winding and having a large opening in the ,other end thereof to permit the insertion of said core and winding therein, a plurality of spaced integral tabs around the edge of said large opening, a circular magnetic cover plate having a plurality of peripherally spaced slots therein to respectively receive said tabs, said tabs being bent to rigidly secure said cover to said casing, said cover plate having a portion thereof in metallic engagement with said magnetic core to hold said core snugly against said end wall of said casing, thereby completing a closed magnetic circuit around said winding, a magnetic plunger projecting partly into said central core opening, resilient means urging said plunger outwardly relative to said core, and means adjustable relative to said casing for limiting inward movement of said plunger produced by energization of said winding.

2. In asolenoid construction having an annular magnetic corev defining a central core opening therethrough and a circumferentially disposed winding on said core, the improvements of a hollow cylindrical magnetic casing having one integrally formed end wall defining a threaded hole, said casing being constructed and arranged to surround said core and winding and having a large opening in the other end thereof to permit the insertion of said core and winding therein, a magnetic cover plate secured across said large opening, said cover plate having a portion thereof in metallic engagement with said magnetic core to hold said core snugly against said end wall of said casing, thereby completing a closed magnetic circuit around said winding, a magnetic plunger having one portion thereof slidable in said central opening and another portion projecting through said cover plate, resilient means urging said plunger' out of said central core opening, means on said plunger engageable with said cover` plate to position said plunger with said one portion pro- Jecting lpartly into said central opening, whereby energization of said winding draws said plunger further into said core opening against the bias of said resilient means, and a core .piece extending into said core opening from the other end thereof to limit the inward movement of said plunger, said core piece having a threaded .portion engageable with said threaded casing open,- ing to adjustably position said core piece relative to said central core, opening.

3. In a solenoid construction having an annular magnetic core defining a central opening therethrough and a circumferentially disposed winding on said lcore, the improvements of a hollow cylindrical magnetic casing having one integrally formed end wall defining an axially located threaded hole, said casing being constructed and arranged to snugly surround said core and winding and having a large opening in the other end thereof to permit the insertion of said core and winding therein, a magnetic cover plate secured across said large opening, said cover plate having a portion thereof in metallic engagement with said magnetic core to hold said core snugly against said end wall of said casing, thereby completing a closed magnetic circuit around said winding, a magnetic plunger having an enlarged head portion slidable in said core opening and a shank portion projecting through said cover plate, a spring surrounding said shank portion on the exterior side of said cover plate and operating between said cover plate and said plunger to urge said plunger outwardly, said plunger having a shoulder between said head,

and shank portions engageable with said cover plate to limit outward movement of said plunger. and a core piece extending into said central core opening from the other end thereof to limit the inward movement of said plunger, said core piece having a threaded portion engageable with said threaded casing opening to adiustably [position said core piece relative to said central core opening.

4. In a solenoid construction having an annular magneticvcore defining a central core opening therethrough and a circumferentially dis- Y 6 posed winding on said core, the improvements of a hollow cylindrical magnetic casing having one integrally formed end wall defining an axially located threaded hole, said casing being constructed and arranged to snugly surround said core and winding and having a large opening in the other end thereof to permit the insertion of said core and Winding therein, a plurality of spaced integral tabs around the edge of said large opening, a circular magnetic cover plate having a `plurality of peripherally spaced slots therein to respectively receive said tabs, said tabs being bent to rigidly secure said cover plate to said casing,v said cover plate having a portion thereof in metallic eng-agement with said magnetic core to hold said core snugly against said end Wall of said casing, thereby completing a closed magnetic circuit around said winding, a magnetic plunger having an enlarged head portion slidable in said central core opening and a shank. portion projecting through said cover plate, a spring surrounding said shank portion o-n the'exterior side of said cover plate and operating between said cover plate and said plunger to urge said plunger outwardly, said plunger having a shoulder between said head and shank portions engageable with said cover.

plate to limit outward movement of said plunger, and a core piece extending into said central core opening from the other end thereof to limit the inward movement of said plunger, said core piece having a threaded portion engageable with said threaded casing opening to adjustably position said core piece relative to said central core openlng.

LELAND H. SNYDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 341,981 Woolson May 18, 1886 1,305,937 Rippl June 3, 1919 2,381,075 Nelsen Aug. 7, 1945 2,414,961 n Mason et al Jan. 28, 194'! 

